A simple graphical method to determine the action of a system of retarders

Abstract

Graphical methods for the study of the transformation of polarised light are essentially pictorial representations of the changes in the polarisation of light as it passes through a system of polarisers and retarders. The analysis is common in both photoelasticity and crystallography. These graphical methods are useful: In finding the changes in the light ellipse parameters as the polarised light passes through various elements of the polariscope, without cumbersome calculations. In finding the characteristic parameters of a particular light path in a three dimensional photoelastic model or for a series of linear retarders. In estimating various errors in the elements of the polariscope. In the proposed method, knowing the characteristic parameters along a particular light path, a simple graphical method for determining the linear retarders which cause the variation of polarisation of light along the light path is illustrated.In a general loaded three dimensional photoelastic model, the characteristic parameters can be found at intervals along the light path. This graphical method makes use of the characteristic parameters and splits the light path into individual retarders which cause the combined effect for the light path.